What is a relational database?

A practical example

Consider a Clients table with basic contact information. That table is self-contained — it only shows what is directly stored in it.

Now imagine you are a SaaS startup and want to track which plan each client is subscribed to. You could add a "Plan" field directly to the Clients table, but that creates two problems:

1. Repeated data — every client on the Smart plan would have the exact same plan details copied row by row
2. High error risk — manual data entry increases the chance of mistakes, and changing one detail (like pricing) would require editing every client record individually

Connecting tables instead

A relational database solves this by letting you connect tables. Instead of copying plan details into every client row, you create a separate Plans table and link it to the Clients table using a "Connect tables" field.

This gives you two immediate benefits:

• From a client record, you can click directly on the plan and see all its details
• From a plan record, you can see every client subscribed to it

The relationship works in both directions. If multiple clients choose the Smart plan, all of them appear when you open that plan — no duplication, no manual updates needed.

How this helps in practice

Relational databases let you organize and reuse data across your entire system. Traditionally, these relationships had to be hard-coded by developers during system design. In Jestor, you can create them directly through the interface with just a few clicks.